The present invention relates in general to the enhanced efficiency of fluid interface surfaces such as airfoils. In particular, the present invention is directed to a dynamic mechanical system for altering lift characteristics of various fluid interface surfaces, for example those that can be used as airfoils or central surfaces on various vehicles, such as aircraft.
Conventional prior art in this field includes basic methods of adjusting lift for fluid interface surface, such as aircraft wings. Bernoulli""s Principal products lift on fluid interface surfaces based on the fact that pressure will be lower on an upper curved surface because the fluid must travel faster over the longer curved surface than a lower substantially flat surface. The result is lift, such as that found on airplane wings.
One of the key goals in aircraft design has always been increasing the lift of any aircraft. The earliest work in this field was done in the early 1920s and 1930s by an individual named Favre, who put a rotating band on a model airplane wing. However, the lower surface of the band was placed internal of the airfoil, thus eliminating the additional lift that had been expected. Additional work had been done by a Dr. V. J. Modi at the University of British Columbia, using rotating cylinders incorporated into an aircraft wing. The lower surfaces of these cylinders were not exposed as were the upper surfaces. In both instances, some increased lift, and decreased boundary layer separation were observed. However, they were not at levels that were expected and the devices were not practical. Also, precise relationships were not developed so that these early devices could not be used in practical or even model aircraft effectively.
Additional use of moveable surfaces on various parts of fluid interface surfaces have continued. Examples of more recent attempts are the techniques found in the file wrapper histories of U.S. patent application Ser. Nos. 08/893,454, 09/865,207, now U.S. Pat. No. 6,322,024, and Ser. No. 09/990,265, all incorporated herein by reference.
Other examples of conventional art use rollers to alter airfoil surface characteristics. Experiments with rotating cylinders, and their effects on boundary layer separation are disclosed in an article entitled xe2x80x9cMoving Surface Boundary-Layer Control; A Reviewxe2x80x9d published in the Journal of Fluids and Structures, 1997. A full review of the conventional art and its limitations is also found in the file wrapper history of U.S. patent application Ser. No. 08/893,454.
The use of rollers or rotating bands in a fluid medium has also been applied to vehicles operating in water, such as submarines. Examples of moving fluid interface surfaces applied to submarines are included in the file wrapper history of the U.S. patent application Ser. No. 08/893,454.
Lift is not the only characteristic considered with respect to rotating bands or rollers on fluid interface surfaces. Turbulence and boundary layer characteristics can also be affected. A more substantial discussion of these effects are found in U.S. Pat. No. 6,322,024, issued Nov. 27, 2001 (a continuation in part of U.S. patent application Ser. No. 08/893,454), incorporated herein by reference.
While a number of fluid interface characteristics have been observed to be adjustable by the techniques ascribed to the conventional art, there appears to be no precise relationships. There are no teachings of exact adjustments in the aforementioned characteristics, such as lift, based on changes in the rotating bands. Without specific relationships, aircraft (or other fluid medium traveling vehicles) cannot be properly designed to take advantage of the lift adjustment effected by rollers or rotating bands. The conventional art provides only the crudest guesses at the relationships between the structure of the bands or rollers, and the lift characteristics achieved thereby. Without clearly defined relationships, practical design is impossible.
Accordingly, a necessary improvement in the conventional art would include accurate relationships between the characteristics of lift enhancement devices, vehicle characteristics, environmental factors, and the effective adjustments in lift caused thereby. This would lead to the practical application of such lift adjustment devices in real aircraft or other vehicles.
Accordingly, it is one object of the present invention to overcome the limitations of conventional art airfoils.
It is an additional object of the present invention to provide a dynamic system for automatically controlling lift in vehicles moving through fluid mediums.
It is again a further object of the present invention to provide a dynamic lift control mechanism that can be used on a wide variety of structures for a wide variety of different vehicles that move through fluid mediums.
It is another object of the present invention to provide a variable lift control system for various types of vehicles moving through fluid mediums, such as air or water.
Still another object of present invention is to provide a variable airfoil configuration capable of adjusting lift characteristics responsive to the circumstances of a vehicle associated with those airfoils.
It is still another object of the present invention to provide a dynamic lift control system capable of clearing an airfoil of ice or other environmental accumulations.
It is again a further object of the present invention to provide a dynamic system capable of altering the performance of airfoil control surfaces.
It is also another object of the present invention to provide a dynamic lift system that permits aircraft to land and take off on shorter runways than is possible with conventional airfoils.
It is still an additional object of the present invention to provide a dynamic lift system that greatly enhances the lift capability of an airplane without a substantial increase in the overall cost of the airplane.
It is yet another object of the present invention to adjust drag on a fluid interface surface.
It is also another object of the present invention to provide additional control systems to increase the responsiveness of any vehicle operating in a fluid medium, in particular airplanes.
It is still a further object of the present invention to provide extremely fast, pre-programmed corrections in all phases of aircraft operation.
It is again an additional object of the present invention to provide additional lift and control devices that integrate into existing aircraft computer control systems. It is yet a further object of the present invention to provide a lift control system that limits fuel consumption.
It is still another object of the present invention to provide a relatively precise relationship between a lift adjusting mechanism, airspeed, aircraft parameters, and resulting lift so that airfoils can be designed to take advantage of the characteristics of the lift adjustment device.
It is yet a further object of the present invention to provide a lift adjustment system having sufficient precision to facilitate exact computer control of an aircraft employing the lift adjustment system.
It is again an additional object of the present invention to provide a lift control system that is capable of substituting for many of the operations of aircraft flaps.
It is still a further object of the present invention to provide a lift control system which can provide an amount of additional lift that is not decreased by the angle of attack of the airfoil on which the device is placed.
It is yet another object of the present invention to provide a lift control system that is capable of creating additional force on the underside of an airfoil.
It is still a further object of the present invention to provide a lift system that is capable of adding significant lift to miniature aircraft, such as unmanned aircraft vehicles (UAV).
It is yet an additional object of the present invention to provide a lift control device that is particularly applicable for low speed operation such as landings and takeoffs.
It is still another object of the present invention to provide a lift control device configured so that the lift provided increases with the size of the lift control device.
It is again a further object of the present invention to provide a lift control device constituted by a rotating band on an airfoil, without the necessity of a motor to rotate the band.
It is still a further object of the present invention to provide a lift control device capable of controlling boundary layer separation.
It is yet an additional object of the present invention to provide a lift control system that allows airfoil designs, which result in decreased turbulence.
It is still a further object of the present invention to provide a lift device which increases lift as the speed of the vehicle, on which the device is attached, is increased.
It is again another object of the present invention to provide a lift device which increases lift as the speed of the surface moving over a wing or other surface is increased.
These and other goals and objects of the present invention are accomplished by an airfoil configured to provide lift. In addition to lift resulting, from the airspeed on the airfoil, including a moving device for incrementing lift, having a rotation speed so that a change in lift is proportional to the square of the rotation speed of the moving device.
Another embodiment of the present invention includes an airfoil having at least one movable band arranged around an upper surface and lower surface of the airfoil. Changes in lift of the airfoil are incremented in accordance with the relationship: xcex94Lxe2x88x9d(RS1)2xe2x88x92(RSu)2; where xcex94L is a change in lift; RS1 is a relative speed of a lower portion of the band on the lower surface of the airfoil, and is equal to Sb+Sa; where Sa is the airspeed and Sb is the band speed; and, RSu is a relative speed of an upper portion of the band on an upper surface of the airfoil, and is equal to Sbxe2x88x92Sa.
Another manifestation of the present invention is found in a method of controlling lift of an airfoil with a moving lift control device. The method includes the steps of developing airspeed on the airfoil, and developing rotational speed of the moving lift control device so that the change in lift is proportional to the square of the combination of airspeed and rotational speed of the moving lift control device.
A further manifestation of the present invention is found in an aircraft having at least one airfoil and a moving device for simulating aircraft flap operation to adjust lift and drag. The moving device includes at least one movable band contoured around at least a portion of at least one of the airfoils.
Another manifestation of the present invention is found in a fluid interface surface configured to provide lift in addition to lift resulting from the fluid speed on said interface surface. The fluid interface surface includes a moving device for incrementing lift. The moving device has a rotational speed operating so that a change in lift is proportional to the square of the rotation speed of the moving device.
Yet another version of the present invention is manifested by a miniature aircraft suitable as a model, or as a UAV. This miniature aircraft has at least one airfoil configured to provide lift in addition to lift resulting from airspeed on the airfoil. The airfoil includes a moving device for incrementing the lift. The moving device has a rotation speed so that a change in lift is proportional to the square of the rotation speed of the moving device.